In the field of industrial kilns, particularly cement kilns, the accumulation of particulate deposits on the inner refractory lining of the kiln is a recurring problem. Buildup in the preheater and riser duct areas can choke off feed pipes and cyclones and greatly affect the efficiency and production performance of the kiln, even to the point of causing unscheduled shutdowns. If the deposits are permitted to accumulate, the high temperatures typically encountered by the interior of the kiln during normal operations will cause the deposits to become encrusted on the kiln's interior surfaces. The exact characteristics of the buildup in preheater towers may vary from plant to plant, and can even vary from hour to hour within the same plant.
Usually, the buildup begins sticking to the walls of the tower with the consistency of talcum powder. Routine cleaning of the deposits is a preferred method of addressing the problem, whereby the deposits are removed before significant accumulation and encrustation occurs. Various strategies in the art for removing deposits during routine cleaning cycles include pneumatic blasting, carbon dioxide explosions, manual air lances, manual jackhammers, and high pressure water blasting. All of these methods cause damage to the refractory lining and expose the operators to dangerous conditions. Moreover, these methods are reactionary to the buildup problem and are intended to minimize rather than eliminate it. These devices generally require access to the interior of the kiln to be effective.
In the case of blast cannons, access is provided to the interior of the kiln through a plurality of spaced apart ports. The ports typically are provided with a refractory protective sleeve for communication between the interior and exterior of the kiln walls. Blast cannons may be provided for each port, or may be moved from port to port to clean various portions of the kiln sequentially. A significant limitation of blast and percussive devices is the difficulty of directing their energy to release particular deposits and their limited effective blast radius.
Increased operational requirements or excessive particulate release may cause the rate of deposit accumulation to exceed the capability of routine cleanings to adequately remove deposit build up. This may lead to encrustation of the deposits on the kiln's refractory walls and occlusion of the access ports. Moreover, incomplete removal of deposits during routine cleaning will also accelerate deposit accumulation and consequent encrustation of the refractory walls as well as occlusion of the access ports.
In the case where the access ports have become fully occluded, many of the devices presently used for routine preventative cleaning are unable to clear the occlusion. In these instances a separate device for penetrating an encrustation to gain access to the interior of the kiln must be installed. In severe cases, the kiln will have to be brought off line before restorative cleaning may be initiated.
The requirement for additional equipment to gain access to the kiln and the manpower required to temporarily install then replace that equipment with the desired cleaning equipment adds significant cost and complexity to the cleaning operation. Moreover, the requirement to bring a kiln off line will adversely effect production capacity.